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<html lang="en">
<head>
  <meta charset="UTF-8">
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  <meta name="viewport" content="width=device-width, initial-scale=1.0">
  <title>Document</title>
</head>
<body>
  <script>
    let arr = [1,2,3,4,5,6,7,8,9,0,9,8,7,6]
    // 判断变量是否是个数组
    // 第一种
    console.log(Object);
    console.log(Object.prototype.toString.call(arr) == '[object Array]');

    // 第二种
    console.log(Array.isArray(arr));
  </script>
</body>
</html>